I'm attempting to set up minimal/simple replication with one master and
one standby using the following pair of identical machines connected
through through a 1-Gb switch:
3.2.0-25-generic #40-Ubuntu SMP Wed May 23 20:30:51 UTC 2012 x86_64
x86_64 x86_64 GNU/Linux
PostgreSQL 9.1.4 on x86_64-unknown-linux-gnu, compiled by gcc
(Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3, 64-bit

The documentation says "To use streaming replication, set up a
file-based log-shipping standby server as described in Section 25.2...."
however I'm not using any of the archive or restore commands but instead
use pg_baseb

I am attempting to upgrade from 8.4 to 9.0 via parallel install of 9.0
along with 8.4. It isn't going well.

I am working on my final 7.4 -> 9.0 upgrade. Data-type (auto-coalesce
and foreign-key), query and encoding issues are resolved. Dump/restore
is tested. But...

I have a few old client systems that are difficult/infeasible to update.
I know the recommended procedure is to update clients ahead of server
but what problems am I likely to encounter connecting to a 9.0 server
from a 7.4 client?

I was working on a test restore and got:
WARNING: column "astring" has type "unknown"

The restore worked correctly - it was a warning not an error - and we
located the cause and corrected it.

I'm weighing options for a new server. In addition to PostgreSQL, this
machine will handle some modest Samba and Rsync load.

I will have enough RAM so the virtually all disk-read activity will be
cached. The average PostgreSQL read activity will be modest - a mix of
single-record and fairly large (reporting) result-sets. Writes will be
modest as well but will come in brief (1-5 second) bursts of individual
inserts.

While we do not manage a "mailing list" in the traditional sense, we do
send a lot of emails (daily/weekly/monthly reports, instant-alert
messages, etc.) where using VERP to track bounces could prove useful.

We run numerous projects with varying requirements and the messages
could be generated by Perl, Python, Bash/mutt, etc. All inbound/outbound
mail is routed through Postfix.

In my ideal world, I would find a magic setting that said, say, "use
VERP for all messages from ... at pinpointresearch dot com" or perhaps from
some specific IP range.

This is not a Postfix question, but...

To integrate a BB into an enterprise requires RIMs back-end
enterprise-server solution which I understand goes well beyond just email.

Traditional carriers selling to the public (non-enterprise users)
typically use RIM's servers in a couple ways. First, you can use a
Blackberry email address. In the case, for example, of T-Mobile, you can
create a Blackberry email account which looks like
<a href="mailto:your.email. ... at tmo dot blackberry.net">your.email. ... at tmo dot blackberry.net</a> (where I believe the tmo is for
T-Mobile users and would change for other carriers).